Use International Mile for UnitLength operations

[nVitius]

I made this PR based on some conversation in this SO post. This patch changes the Coefficient for the mile to 1609.344, to be in-line with the official definition of the "international mile".

From the NIST's Conversion Factor's for General Use handbook:

The existing Coefficient leads to an incorrect result. This can be seen by trying to convert 1 mile to feet (1 mile should be 5280 feet):
1 * 1609.34 / 0.3048 = 5279.9868766404199475065616797900262467191601049868766404199475065...
Using the standard 1609.344 instead gives 5280.

The Coefficients for inches, feet, and yards are all correct.

[spevans]

@swift-ci test

[nVitius]

@spevans @amomchilov
I believe I fixed the failing test cases.

I'm not 100% sure about the TestFoundation.TestMeasurement-testLoadedValuesMatch test.

It uses the .archive fixtures. As far as I can tell, those were created with NSKeyedArchiver. I'm not sure how to replicate that, but I think it's just a binary plist. I converted to XML and back to binary after updating the incorrect property (the coefficient for mile).

Will you please re-run the tests?

[spevans]

@swift-ci test

[nVitius]

Looks like the changes allowed the tests to pass.

@amomchilov @spevans
Not sure what the protocol is for merging PRs. Just pinging you two to make sure you've seen this. Let me know if you need anything else from me. Thanks!

[millenomi]

@nVitius does your patch correspond to Darwin behavior? We try to keep things working 1:1 bug-for-bug where possible.

[nVitius]

@millenomi Looking through the docs, it would seem like Darwin also has this issue:
https://developer.apple.com/documentation/foundation/unitlength?changes=latest_minor

I sent a report via FeedbackAssistant for now; I'm not sure where the best place to report this would be.

[amomchilov]

We try to keep things working 1:1 bug-for-bug where possible.

Oh jeeze. That's unfortunate, but understandable.

I've had better success piping my bug reports to /dev/null than sending them into feedback assistant 😅

[millenomi]

sighs

Can you post your FB number so I can pass it on internally?

[amomchilov]

Pinging @nVitius, he's the one who submitted a bug report.

[nVitius]

The FB number is: FB9542852

[millenomi]

Thank you. I'm going to close this for now, but it was important and I'll make sure the issue is seen so we can ultimately fix it here as well.